1. Field of the Invention
The present invention relates to a high-frequency magnetron plasma apparatus, and particularly to the construction of a magnetic shield disposed in a high-frequency magnetron plasma apparatus.
2. Description of the Related Art
FIG. 5 illustrates an example of conventional high-frequency magnetron plasma apparatus. Where plasma is excited by using the apparatus shown in FIG. 5, a gas is introduced into a vacuum chamber 501 having a gas inlet tube 512 and a gas discharge opening 513, and high-frequency electric power is applied to a plasma exciting electrode 502 from a high-frequency power source 508 through a matching box 507 to excite the plasma between the plasma exciting electrode 502 and a susceptor electrode 509.
Magnets 504 are disposed in the plasma exciting electrode 502 in order to increase the density of the plasma between both electrodes, and a magnetic shield 505 for preventing leakage of a magnetic field, comprising a high-permeability material is also provided for preventing the magnetic field from leaking to the vicinity of the plasma exciting electrode and the plasma from extending thereto. The susceptor electrode 509 is earthed through a band pass filter 510, a high-frequency ammeter 511 for measuring the susceptor current being provided in the course of earth. Reference numeral 506 denotes an insulator for insulating the vacuum chamber 501 from the electrodes.